function after(times = 0, cb) {
    let count = 0;
    return function() {
        count++;
        console.log(count);
        if (count >= times) {
            cb();
        }
    }
};
let fn = after(3, function() {
    console.log('really exec');
})
fn()
fn()
fn();

let fs = require('fs');
fs.readFile('./README.md', 'utf-8', function(err, data) {
    console.log(err, data);
})